Kinetic Resolution of Chiral Cyclohex-2-enones by Rhodium(I)/binap-Catalyzed 1,2- and 1,4-Additions

The feasibility of kinetic resolutions of racemic monosubstituted cyclohex-2-enones by Rh/binap-catalyzed reactions was investigated. 1,2-Addition of AlMe₃ to the 5-substituted derivatives furnished allylic alcohols in the matched case, while the less reactive enantiomers were either left over or transformed into <i>trans</i>-3,5-disubstituted cyclohexanones in parallel or sequential 1,4-additions. Altogether, these represent regiodivergent reactions on racemic mixtures. In contrast, 1,4-addition of aryl groups led to inferior results since either catalyst or substrate control dominated

Rhodium-Catalyzed Enantioselective Addition of Organoaluminum Reagents to <i>N</i>‑Tosyl Ketimines

Rhodium­(I)/Binap complexes catalyze highly enantioselective additions of methyl- and arylaluminum reagents to cyclic α,β-unsaturated <i>N</i>-tosyl ketimines. Depending on the solvent and substituents at the ring, the reaction occurs either in a 1,2-manner to deliver α-tertiary allylic amines or in a 1,4-manner to yield, after subsequent reduction, 3-substituted cycloalkyl amines. Well known in the case of the respective cycloalkenones, these first transformations of the aza-analogues enable the synthesis of amine structures of pharmaceutical and biochemical interest